Waveguide element operable up to terahertz frequencies including a dielectric portion having periodic holes of a specified period formed therein and which is mounted on a support substrate

A waveguide element, comprising:

• a dielectric portion having holes periodically formed in a substrate made of a ceramics material;
• a low-dielectric constant portion having a dielectric constant smaller than a dielectric constant of the dielectric portion;
• and
• a support substrate arranged below the dielectric portion, the support substrate being configured to support the dielectric portion,
• wherein the waveguide element has a normalized frequency P/λ of from 0.05 to 0.3 where P represents a period of the holes and A represents a wavelength of the electromagnetic wave,
• wherein the waveguide element is configured to guide an electromagnetic wave having a frequency of 30 GHz or more and 20 THz or less, and
• wherein a frequency range of the electromagnetic wave in which an absolute value of a propagation loss becomes 1 dB/cm or less is 50 GHz or more.